It is known to provide a vehicle having a plurality of subsystems which can be operated in different configurations to suit different driving conditions. For example, automatic transmissions may be controlled in a variety of modes such as sport, manual, winter or economy. In each mode, subsystem control parameters such as accelerator pedal response and conditions under which changes between gear ratios take place may be modified so as to suit the conditions of the terrain or the particular taste of the driver. It is also known to provide air suspensions with on-road and off-road modes. Stability control systems can be operated at reduced activity in certain modes so as to give the driver more direct control, and power steering systems can be operated in different modes to provide a varying level of assistance depending on driving conditions.
In a known vehicle control system allowing selection of control modes optimised for different driving conditions, mode selection is entirely manual. The control system (which may also be referred to as a terrain response (TR) control system) responds to a user request for operation in a given control mode according to the position of a control knob. If the control knob has been left in a given mode (such as a grass/gravel/snow (GGS) mode) at key-off then the control system will assume the GGS mode at the next key-on, unless the control knob has been adjusted. Thus the position of the control knob determines the control mode that will be assumed by the controller.
Embodiments of the present invention have automatic mode selection functionality and may operate as described elsewhere herein. Embodiments of the invention may for example employ a multi-stable knob for mode selection, optionally of the kind described herein. In some embodiments the physical position of the knob is not indicative of selected mode. In embodiments having a rotatable knob the knob may be rotated through an angle greater than 360°.
It is to be understood that in some embodiments of the present invention the control system is able to determine confidently the type of terrain over which the vehicle is moving and determine the most appropriate control mode in a relatively short distance of travel (approximately less than two car lengths in some embodiments). When a vehicle moves from rest following key-on, the control system can therefore determine the most appropriate terrain relatively quickly and be ready to command a change in selected mode if required.
The applicant has recognised that since the most appropriate mode may be determined relatively quickly, the vehicle speed may be relatively low when the determination has been made. Furthermore, whether or not the speed is low, it may be possible to command the change relatively soon after the vehicle commences movement. A user of the vehicle may be particularly sensitive to vehicle motion and response of the vehicle to control inputs such as accelerator pedal input. If the control system commands the change as soon as it has determined that a change is needed, immediately or soon after starting, a user may perceive that a change in vehicle response has taken place and may perceive the change as a fault. The change may be detrimental to vehicle composure and user enjoyment.
Furthermore, if a user moves a vehicle between forwards and reverse gears directly after key-on, a change in selected mode may take place as a user changes vehicle direction. The user may readily detect the change, and again may perceive the change in behaviour as a fault.
It is desirable to provide an improved control system for a motor vehicle operable in different configurations.